Thermoelectric switch mechanism



Oct. 31, 1944. a ER 2,361,397

THERMO-EIJECTRIC SWITCH MECHANISM Filqd May 12, 1941 2 Sheets-Sheet l JLyJ,

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i FINTOR ATTORNEYS Oct. 31, 1944. e. A. GUENTHER THERMO-ELECTRIC SWITCH MECHANISM Filed May 12, 1941 2 Sheets-Sheet 2 INVENTOR Patented Oct. 31, 1944 UNITED STATES PATENT'OFFICE 2,361,397 THERMOELECTRIC SWITCH MECHANISM George A. Guenther, Buffalo, N. Y., assignor to Leon H. Ballou, Lockport, N. Y.

Application May 12, 1941, Serial No. 392,998

10 Claims.

This invention relates to a thermostatic switch mechanism which is used in connection with the control mechanism of gas heaters and more particularly as part of the means for shutting off the gas supply to the main burner if the flame of the pilot burner is extinguished and thereby prevents the premises from being dangerously flooded with raw or unburned gas.

It is the. object of this invention to provide improved thermostatic switch means for this purpose which are relatively simple in construction, eflicient in operation, not liable to get out of order and capable of being manufactured and maintained at low cost. This application is, in part, a; continuation of my copending application Ser. No. 288,404 for Heating apparatus, filed Aug. 4, 1939. i

In the accompanying drawings:

Fig. 1 is an elevation, partly in section, of a gas heating apparatus embodying this invention.

Fig. 2 is a fragmentary vertical section taken on line 22,' Fig. 1.

Fig. 3 is a fragmentary vertical section, on an enlarged scale, taken on line 3-3, Fig. 1.

Fig. 4 is a vertical section, taken on line 4-4, Fig. 3.

Fig. 5 is a horizontal section, taken on line 5-5, Fig. 3.

Fig. 6 is a fragmentary vertical section showing 'a modification of this invention.

may be advantageously used in connection with various kinds of gas heating apparatus but more particularly in connection with a heating apparatus of this'character in which the gas is burned in a combustion chamber under vacuum, as

shown for example in Letters Patent of the United States No. 2,134,083. Referring more particularly to Fig. 1, the numeral I 0 represents the combustion chamber of the heating apparatus having outlets H adjacent to its top through which the gaseous products of combustion are withdrawn by an exhausting device which produces a vacuum in this chamber, as explained in "the above mentioned patent.

Within the lower part of this combustion chamher is arranged a main gas burner l2 which may be of any suitable construction and receives a combustible gas'and air mixture through a supply conduit the discharge part 13 of which extends vertically through the bottom of the combustion chamber and carries the main burner at its upper end. At its lower end this mixture discharge conduit 13 is connected with a raw gas supply pipe l4 and an air supply pipe IS. The raw gas supply pipe 14 containsan automatic pressure reducing valve l6 adjacent to its inlet, a suction operated safety valve l! adjacent to the mixture pipe or conduit 13, a manually operable regulating valve I8 infront of .the safety valve, and an electrically operated control valve l9 arrangedbetween themanually operated valve l8 and the automatic. reducing valve I6, as in the patent referred to.

Opening of the closure member of the control valve 19 is effected by closing an electric circuit which contains a solenoid electromagnet 20, the movable co're of-which is connected with this closure, and opening of this closure iseffected by breaking this circuit in the manner described in this patent. An alternating electric current for operating the solenoid magnet is supplied by feed lines 2| from which the current is stepped down to the circuitof the solenoid by a transformer 22 and converted into a direct current by a rectifier 23. I

The premises or room which is to beheated by this apparatus containsa room thermostatic electric switch 24 which operates to closethe circuit of the solenoidmagnetcoil and open the control valve l9 to permit the flow of gas to-the main burner I 2 when the temperature in the room drops below normal and to open this :cir-

cult to permit the control 'valve- 19 to close and shut off the flow of raw'gas to the main burner when the temperature -.-in the room rises above normal. I

The pipe 15 supplying air to the burners is provided withan air filter 25 and a hand operated valve 26 for regulating the amount of air supplied to the burners.

Adjacent to the'main burner is arranged a pilot burner 21 the flame of which normally burns constantly and operates to relight the gaseous mixture issuing from the main burner whenever the flow of gas to the latter is resumed after having been extinguished by the control means due to'the rise of the room temperature above normal.

At its upper end this pilot burner is provided with a horizontal deflector 28-whereby the flame is not only directed lengthwise over the main burner but also laterally to one side thereof for cooperation with the thermostatic electric switch means forming the subject of this invention. In addition to the deflector the pilot burner 21 is provided with an auxiliary gas outlet opening 29 which directs the burning gas issuing therefrom toward the thermostatic electric control mechanism for additionally heating the same under normal conditions. This pilot burner is mounted on the upper end of a vertical supply pipe 30 passing through the bottom of the combustion chamber and constantly supplied with a combustible gas by a pipe 3| connecting the lower endcf .the pilot burner pipe with the inlet portion *32 Of the .gas supply pipe between the safety valve |6 and the automatic electric control valve IS.

The improved thermostatic electric switch mechanism for causing the-control-valve IE! to be automatically closed inaccordance with this invention when the pilot light fails to burnais constructed as follows:

Adjacent to the front outer-side of the pilot burner 21 is arranged a thermostat *element which is responsive to the heat of the pilot burner 'fiame'andwhichis made of a single metal in the form of anendless loopor closed frame and has one of 'its-pa'rts arrange'd adjacent to the outlet of l the pilot burner so "that the flame from the latter-'str'ikesthe respectivepart of the loop while the remaining parts'of the same are not heatedywhereby upon alternately heating and cooling one part only of tliis loop the same will expand and -contract circumferentially. This movementof the thermostat loop'is utilized to close-and open an 'electi'ic eircuit'which contains the coil of the solenoid magnet" 20 50 that when a flame'of the-pilot burner heats thelrespective part-of the thermostat loop'the control valve will'be opened but=when theflame of the-pilot burneris extinguished and the-respective part of the thermostat loop is not heated, then the "controlvalve |9"will be closed and prevent gas from flowing-to the mainburner.

' This thermostat element preferably comprises an upper section having'the' form of-an upwardly curvedbow 33-the uppermost part-of which -is 'arrangedbetween "the upper end outlet of the pilot burner and the side outlet-230i the same and vertical legS'34/34l "projectingdownwardly from opposite en'ds-of-this'bow, and a lower section having'theform of a horizontal bar 33-which is provided at one end with an upturned "lug 36 which is connected 'with'theleg 34-0f the bow and a downturned lug 31 at its opposite end which is connected'by spot welding or otherwise to theother leg'34l of' the bow,-as shown in Fig. 4. At one 'point in the circumference-of the thermostat'loop the same is fixedly secured oranchored while the rest of this loop is free to move 'circumferentially, this anchoring point being preferably located at theupturned lug 36 atone 'end of the-bar-section 35 and the adjacent end of the leg 34 of the bow section,-which lug and leg 'are'connected by bolts 38 with an upright post 39 forming one-end of a'guard'or protecting casing or housing which-encloses'the lowerbar section 35and 'side legs'of the thermostat member while another uprightpost 40 arranged adjacent to the 1 opposite 'end 'of this bar section' and the respec- =tive-sideleg 341 forms the other-end wall of this housing.

The 'upper ends of these posts .39, '40 termi- "nate horizontallyinline with the top of the bow :"33 'of the upper thermostat loop-section'and serve to confine the heat of the pilot 'burnerflame -around the'bow'portion of the upperthermostat section-and permit the same to.fiow only vertical'ly and laterally relative to this bow but not 'lengthwise'of' the same, thereby ensuring prompt .plate 4| movement of the thermostat loop in response to the presence or absence of a pilot burner flame. The two posts 39, 40 are connected at their lower ends with a horizontal plate 4| and at opposite edges of their lower parts by inner and outer upright longitudinal side walls 42, 43, which together form the lower stationary section of the housing or casing which protects the lower parts of the thermostat loop from the heat of the pilot burner flame and keeps this part of the loop comparatively cool. This lower housing section may be held in place in any suitable manner, this being effected in the present case by screws 44 which "fasten the bottom 4| of the thermostat loop housing to a plate 45 forming part of the bottom of erablycomprises front and rear upright plates 46, 41 extending lengthwise across the front and rear walls 42, 43 and the adjacent parts of the posts 39, 4!) of the lower stationary thermostat housing section and provided respectively at their vertical edges with flanges 48,49 which are detachably secured byscrews 50, 5| with the outer sides of the end walls formed by thejlower parts of the legs 39, 40 and horizontal overlapping flanges 52, 53 arranged at the upper ends of the longitudinal walls, 41 and extending across the space bet-weentthefside parts of said thermostat loop but terminatingxshort' of'the inner sides of the parts 39, 40 soas to'iorm openings54, 55 through which the *side .parts of thisloop and the adjacent parts of said posts 39, 40 project, as shown inFig. 4. By these means the lower parts of the thermostat loop are guarded or shielded from theheat ,of the pilot burner flame, thereby confining the circumferentialdistortion or expansion and :contraction of the thermostat loop to the'upper part thereof whichis exposed to the heat of thepilot burner flameand ensur ing a greater circumferential movement of the lower part of this loop for use in effectively open- .ing and closing-the circuitof the "solenoid magnet 20. This construction of theupper or cover section of the thermostat loop housing'permits of conveniently assembling the the same and also disassembling the same for inspection, adjustment and repairing. The electric switch which is opened and closed by the circumferential movement of the thermostat loop preferably comprises a stationary contact 56 and a movable contact 51 adapted to be moved into and out of engagement with the stationary contact,.these contacts normally forming part of the electric circuit which .includes the coil of the solenoid magnet 20, the room thermostat switch, the rectifier and one side of the transformenas shown inFig. 1.

The stationary contact 56 is mounted on the inner side of the lower part of an upright tube 58 preferably forming a downward extension of the lower section of the thermostat loop housing and connected at its upper e d with t e bottom thereof and themovable contact 51 is arranged in the lower part of this housing tube and mounted on the lower end of an upright pendulum bar 59 which latter is connected at its upper end with the leg 34| of the bow of the thermostataloop .at apoint remote from the bolts 38 used for anchoring the loop to a fixed part, this connection between the pendulum bar and the bow leg 34| being preferably substantially diametrically opposite to said'anchoring point of the loop. as shown in Fig. 4. During the operationof the thermostat loop the leg 34| of the'bow 33'remote;from the'anchorage 38-forms the upper arm and the pendulum bar 59 forms the lower arm of a switch lever which turns about a floating fulcrum formed at 60-between the lug 31 of the loop bar 35 and the bow leg 34L Due to this construction heating of the bow of the thermostat loop by the flame of the pilot burner, this bow will be expanded circumferentially and cause the upper arm 34l of the switch lever to be moved outwardly, as indicated by th'e arrow 6| associated with this arm in Fig. 4, while the lower arm 59 of this lever will be turned inwardly or in the opposite direction, as indicated by the arrow 62, thereby engaging the movable switch contact 51 with the fixed contact 56 and closing the electric circuit of the solenoid magnet 20, so that if this circuit was also closed by the room thermostatic switch 24, the control valve l9 will be held open and permit gas to flow to the main burner. When, however, the flame of the pilot burner is extinguished due to failure of the gas supply or other reason and the bow of the thermostat loop is no longer heated, then the bow contracts and the circumferential length of the loop is reduced, therebycausing the upper and lower arms 34! and 59 of the thermostatic switch lever to turn about the fulcrum 6D in a direction opposite to that indicated by the arrows SI, 62, whereby the movable contact 51 is disengaged from the fixed contact 56 and the electric circuit containing the coil of the solenoid magnet 20 is broken and the control valve I9 is closed so that no more gas can flow to the main burner l 2. When the gas is again supplied at the required pressure through the main supply pipe the pilot burner 28 is relighted and the safety valve 11 is again opened, thereby heating the thermostat loop by the flame of the pilot and causing the control valve I9 to be again opened automatically and retained in this condition so long as the pilot flame burns.

The tubular extension 58 is preferably arranged centrally relative to the thermostat loop to render this mechanism compact and also symmetrical. For the purpose of adapting the lower pendulum arm 59 of the loop switch lever to this relative arrangement of the tubular extension the lower part of this pendulum lever arm is offset inwardly relative to the upper part thereof by forming the intermediate part of the same into a horizontal web 63, as shown in Fig. 4. When assembling this thermostatic switch may be easily bent to bring the contact 51 at the lower end of the pendulum arm 59 into the desired relation with the fixed contact 56. This bending may be eflected by means of a pair of pliers which are passed through an opening 64 in the outer wall of the lower section of the thermostat loop housing which opening is normally closed by the front wall 46 of the upper section of the thermostat loop housing, as shown in Figs. 3 and 4. Fine or close adjustment of the movable contact 51 is effected by connecting the same with the lower end of the pendulum arm 59 by means of a leaf spring 65 which tends to move this contact toward this pendulum arm and engaging the spring 65 and adapted to move the contact away from said arm.

Accidental displacement of the adjusting screw 66 is prevented by a detent spring 61 mounted on the pendulum arm and frictionally engaging the threaded part of this screw. The latter is accessible from the exterior of the housing tube 58 by a hole 68 formed in this tube in line with this screw which hole is normally closed by a plug 69. At its lower end the housing tube is provided with the web part 63 arm and an adjusting screw 65 working in a threaded opening in the I the upper end of other end of the how has the adjacent to the contacts 56, 51 sand paper or other means may an opening 10 through which be inserted for in operative condition, which openin is normally closed by a screw plug 1|. It will thus be noted that all parts of this thermostatic switch are contained within an enclosure which is cut on from the outer atmosphere and communicates only with the interior of the combustion chamber In and therefore subject to the suction eflect of the fan or other exhausting device which is connected with the outlets H of the combustion chamber for producing a vacuum in the latter while the heater is operating normally in the manner described in said patent. Deflecting means are provided for directing the flame of the pilot burner toward the upper part of the thermostat loop and causing the latter to operate promptly and reliably. The preferred construction of these deflecting means comprise an outer U-shaped deflector section having an upright web 12 extending circumferentially of the bow of the thermostat loop, a lower horizontal flange 13 projecting inwardly from the lower end of said bow toward the pilot burner and secured to said bow, and an upper horizontal flange 14 projecting from said web toward said pilot burner. Within the outer deflector section is arranged an inner U-shaped deflector section having an upri ht web 15 engaging said outer web and having a lower horizontal flange 16 connected with the bow of the thermostat loop and an upper horizontal flange 11 projecting inwardly from the inner web toward the pilot burner and spaced from the upper flange 14 of the outer deflector section.

For the purpose of still further increasing the heat transference from the flame of the pilot burner to the bow of the thermostat loop a bafile tongue 18 is stamped out of the upper flange of the outer U-shaped deflector section and bent downwardly into an inclined position thereto, as shown in Fig. l. These deflecting means operate to intercept more of the flame of the pilot burner and absorb its heat and transfer the same to the bow of the thermostat loop so that the latter will expand qu ckly when the pilot burner is lighted and open the control valve [9 for supplying gas to the main burner. Owing to the differential in the temperature of the heated upper part of the thermostat loop and the protected lower part of this loop, the latter will contract quickly when the pilot burner is extinguished and thus cause the control valve I9 to close promptly and prevent raw gas from entering the room which is being heated.

In the modified form. of this invention shown in Fig. 6, no part is employed which is equivalent to the cross bar 35 in the construction shown in Figs. 1-5 but in this modified form the thermostatic member has the form of a bow or inverted letter U the central part 33| of which is preferably curved upwardly and one end thereof has the form of a vertical leg 342 which is r gidly secured by a bolt 38! to the adjacent upright post 3!" of the stationary housing or frame while the form of an upright leg 343 which turns in a vertical plane around a horizontal pivot pin 6M passing through a lug 35! on the inner-side of the leg 343 and a web 31! on the inner side of the adjacent post 40! of the stationary housing or frame. At its lower end the pivoted leg 343 is provided with a shifting arm which projects downwardly from the opposite side of the axis of-the pivot pin 6!!! keeping these contacts clean and,

about which the-leg 343 turns, this shifting arm preferably consisting of an upper section 344 forming a downward extension of the leg 343 and a lower section fifilwhich carries the movable contact 51. I

In other respects this modification of the invention is constructed and operates similar to the construction shown in Figs. 1 to 5. As the flame issues from the burner opening 29, adjacent to which the central upwardly curved part 33l of the thermostatic member is arranged, this member expands the bulges upwardly, whereby the pivoted leg 343 is moved horizontally outward and the shifting arm sections 344, 591 are moved horizontally inward and turn about the axis of the pivot pin Bill in the manner of a lever, thereby. causing themovable contact 51 to be engaged with the stationary contact'56 and the circuit of the magnetZO to be closed and the central valve -l9 held open so that gas is permitted to flow to the main burner l2 and the pilot burner 21. When, however, no gas issues from the pilot burner 21 and the flame is extinguished, then the cooling of the bow shaped thermostatic member will cause the same to contract and cause its pivoted leg 343 to turn inwardly about the axis of the pivot pin SDI, whereby the shifting arm 344, 59l will be moved outwardly and disengage the movable'contact 51 from the fixed contact 56, thereby breaking the electric circuit containing the solenoid magnet 20 and causing the control valve I9 to be closed and prevent the flow of gas to the main and pilot burners.

I claim'as my invention:

1. A thermostatic electric switch mechanism 1 comprising two switch contacts one of which is fixed and the other movable toward and from the fixed contact for closing and opening an electric circuit, a metal endless loop which is anchored at one part of its periphery on a fixed support and which includes an upwardly curved bow and upper central part of which is adapted to be heated and cooled and one end of which is secured to said support and the other end thereof being free to move circumferentially and a lower straight bar arranged tangentially relative to said bow and having one of its ends fixed and secured to said fixed support and having its opposite end free and connected with the free movable end of said bow, and means for causing the movable contact to move circumferentially with the movable ends of said bow and bar including a laterally projecting arm having its inner end connected with the movable ends of said bow and bar and havin its outer end connected. with said movable contact.

2. A thermostatic electric switch mechanism comprising two switch contacts one of which is fixed and the other movable toward and from the fixed contact for closing and opening an electric circuit, a metal endless loop which is anchored at one part of its periphery on a fixed support and which includes an upwardly curved bow the upper central part of which is adapted to be heated by a flame and one end of which is secured to said support and the other end thereof being free to move circumferentially, and a lower straight bar arranged tangentially relative to said bow and having one of its ends fixed and secured to said fixed support and having its opposite end free and connected with the free movable end of said bow, means for causing the movable contact to move circumferentially with the movable ends of said bow and bar, and deflecting means arranged on the upper part of said bow and adapted llil to direct said'flame toward the respective part of said bow.

3. A thermostatic electric switch mechanism comprising two switch contacts one of which is fixed and the other movable toward and from the fixed contact for closing and openingan electric circuit, a metal endless loop which is anchored at one part of its periphery on a fixed support and which includes an upwardly curved bow the upper central part of which is adapted to be heated by a flame and one end of which is secured to said support and the other end thereof being free to move circumferentially, and a lower straight bar arranged tangentially'relative to said bow and having one of its ends fixed and secured to said fixed support and having its opposite end free and connected with the free movable end of said bow, means for causing the movable contact to move circumferentially with the movable ends of said bow and bar; and deflecting means arranged on the upper part of said bow and adapted to direct said flame toward the respective part of said bow, comprising an outer U-shaped deflector section which has an upright web extending circumferentially of said bow, a lower horizontal flange secured to the bow and projecting toward said flame and an upper horizontal flange projecting toward said flame, and an inner U- shaped deflector section having an upright web engaging with the inner side of the outer deflector section, a lower flange secured to the upper side of the lower flange of the outer deflector section and to the adjacent part of the bow, and an upper flange which projects from the upper end of the inner web toward said flame and is spaced from the upper flange of said outer deflector section.

4. A thermostatic electric switch mechanism comprising two switch contacts one of which is fixed and the other movable toward and from the fixed contact for closing and opening an electric circuit, a metal endless loop which is anchored at one part of its periphery on a fixed support and which includes an upwardly curved bow the upper central part of which is adapted to be heated by a flame and one end of which is secured to said support and the other end thereof being free to move circumferentially, and a lower straight bar arranged tangentially relative to said bow and having one of its ends fixed and secured to said flxed support and having its opposite end free and connected with the free movable end of said bow, means for causing the movable contact to move circumferentially with the movable ends of said bow and bar; and deflecting means arranged on the upper part of said bow and adapted to direct said flame toward the respectivepart of said bow, comprising an outer U-shaped deflector section which has an upright web extending circumferentially of said bow, a lower horizontal flange secured to the bow and projecting toward said flame and an upper horizontal flange projecting toward saidflame, and an inner U- shaped deflector section having an upright web engaging with the inner side of the outer deflector section, a lower flange secured to the upper side of the lower flange of the outer deflector station and to the adjacent part of the bow, and an upper flange which projects from the upper end of the inner web toward said flame and is spaced from the upper flange of the outer deflector section said upper flange of the outer deflector section being provided with a baffle tongue which is stamped downwardly-out of the metal of the respective flange and inclined relatively to the same.

5. A thermostatic electric switch mechanism comprising two cooperating switch contacts which form part of an electric circuit and one of which is movable and the other stationary, an endless loop of metal having its upper part arranged to be heated by a flame and secured at one of its sides to a fixed support while its opposite side is free to move circumferentially and operatively connected with said movable switch contact, and a guard which protects the lower part of said loop from the heat of said flame and which includes a housing enclosing the lower part of said loop and said movable switch contact and which is provided adjacent to its opposite lateral sides with openings through which extend the opposite lateral parts of said loop.

6, A thermostatic electric switch mechanism comprising two cooperating switch contacts which form part of an electric circuit and one of which is movable and the other stationary, an endless loop of metal having its upper part arranged to be heated by a flame and secured at one of its sides to a fixed support while its opposite side is free to move circumferentially, an arm connected with the circumferentially movable part of said loop and carrying said movable switch contact, and a housing enclosing the lower part of said loop and having a tubular extension which receives said arm.

7. A thermostatic electric switch mechanism comprising two cooperating 'switch contacts which form part of an electric circuit and one of which is movable and the other stationary,

an endless loop of metal having its upper part arranged to be heated by a flame and secured at one of its lateral sides to a fixed support while its opposite side is free to move circumferentially, an arm connected with the circumferentially movable part 01 said loop and carrying said movable switch contact, and a housing enclosing the lower part of said loop and having a tubular extension which receives said arm, said tubular extension being arranged centrally in line with said loop, and said arm having an upper part arranged at the side of said housing and a lower part which is offset from the upper part and arranged in said tubular extension.

8. A thermostatic electric switch mechanism comprising two cooperating switch contacts which form part of an electric circuit and one of which is movable and the other stationary, an endless loop of metal having its upper part arranged to be heated by a flame and secured at one of its lateral sides to a fixed support while its opposite side is free to move circumferentially, an arm connected with the circumferentially movable part of said loop and carrying said movable switch contact, and a housing enclosing the-lower part of said loop and having a tubular extension which receives said arm and also having one of its walls provided with an opening through which said arm may be adjusted and a movable wall which covers said opening.

9. A thermostatic electric switch mechanism comprising two cooperating switch contacts which form part of an electric circuit and one of which is movable and the other stationary, an endless loop of metal having its upper part arranged to be heated by a flame and secured at one of its sides to a fixed support while its opposite side is free to move circumferentially and operatively connected with said movable switch contact, and a housing having a lower section which encloses the lower part of said loop, and posts arranged adjacent to the lateral sides of said loop and forming between them an upwardly opening space which receives said posts.

10. A thermostatic electric switch mechanism comprising two cooperating switch contacts which form part of an electric circuit and one of which is movable and the other stationary, an endless loop of metal having its upper part arranged to be heated by a fiame and secured atone of its sides to a fixed support while its opposite side is free to move circumferentially and operatively connected with said movable switch contact, and a housing which encloses the lower part of said loop and comprises a lower stationary section having a bottom arranged below this loop, and an upper section having side walls engaging the side walls of the lower section and provided at their upper edges with top flanges which overlap within said loop.

GEORGE A. GUE'NTHER. 

